Najib, who is the son of Malaysia's second prime minister and Defence Minister Hishammuddin Hussein's cousin, is hardly a well-known figure on the international political scene.

Around the region, though, he is recognised as an astute politician but one who carries the baggage of multiple controversies.

From allegations of being connected to the murder of a Mongolian model and translator Altantuya Shaariibuu in 2006 to a so-called dodgy deal involving the purchase of two Scorpene-class submarines from the French in 2002 when he was defence minister, Najib has many other problems besides trying to run his country smoothly.

Despite the controversies, Najib has come a long way. He became leader of the country in 2009. He had studied industrial economics at the University of Nottingham in England and graduated in 1974. Before being elected unopposed as an MP at just 23, Najib spent some time working at Malaysian oil and gas company Petronas.

The West only seems to remember Najib and Malaysia for the poor handling of Flight MH370, which vanished in early March and remains missing.

But, by striking an agreement with Borodai, he achieved something tangible, which the political heavyweights failed to do despite grandiose speeches and threats of sanctions.

"Many criticised the Russians and the separatists, but no one took concrete action except Najib," said Sivamurugan Pandian, a political analyst from Universiti Sains Malaysia. "He can utilise this situation to win support at home but he needs to ensure that his team can complete whatever was promised."

A few days ago, Najib flew to the Netherlands where at a joint press conference with his Dutch counterpart Mark Rutte, he demanded an immediate ceasefire by both Ukrainian and separatist forces to allow investigators safe access to the crash site.

"The way Najib handled the MH17 challenge boils down to his modus operandi," said Alan Chong, an expert in Southeast Asian politics at the S. Rajaratnam School of International Studies in Singapore. "As a seasoned politician, using back channels and cutting deals are classic moves from his playbook, similar to former prime minister Mahathir [Mohamad]."

Najib, whose step-grandmother was one of the 298 people on board MH17, had been on the ball from the beginning - taking charge of the first press conference even before the sun came up on July 18 at 4am, just a few hours after the Boeing jet had disappeared from radar.

A local reporter said he was surprised by the urgency displayed. "I guess they must have learned their lessons from MH370," the journalist said.

International media, which had criticised the Malaysian government for its handling of the MH370 saga, warmed to Najib and painted a picture of a hero.

lauded his silent diplomatic approach, which he adopted despite some factions in Malaysia criticising him initially for not being loud enough in condemning Russia and the separatists for their lack of cooperation.

"Part of the praise may have to do with the fact that expectations were not high after the handling of Flight 370, but progress is to be welcomed," said Chong Ja Ian, from the political science department at the National University of Singapore.

However, once the latest crisis abroad is resolved, domestic challenges remain for Najib and his United Malays National Organisation party.

"Najib has always been more popular than his own party, and the way he handled MH17 might have made him more popular but this is temporary. People will forget," said Wan Saiful Wan Jan, chief executive at the Institute for Democracy and Economic Affairs, a Malaysian think tank.

Allegations of corruption remain rife and there are structural issues with the economy. Proper distribution of benefits to large swaths of society remains problematic as well.

"Najib's greatest challenge is not that he has any one of these issues looming large, but that they are all happening simultaneously," said Chong Ja Ian. "He must deal with them concurrently although his constituents may be demanding different things."

Recent controversies surrounding race and religion in the Muslim-majority country of 30 million people has particularly rattled urban Malaysians.

Following pressure from ultra-conservative religious groups, the word "Allah" - God in Arabic - was banned from being used in a local Catholic newsletter, causing friction between some Christians and Muslims. Bibles translated in Malay are also not allowed to use the word.

Extremist groups such as Ikatan Muslimin Malaysia (ISMA) have been spouting right-wing messages warning majority Malays that their sovereign rights are under threat from other races. The group has also warned that Malaysia must not become a liberal democratic country which it says is what the "Zionist movement" wants.

Perkasa, formed after the 2008 general election, is another powerful Malay-rights group which uses racial provocation and, occasionally, violence to get its message across. The group has been referred to as "fascist monsters" by the opposition.

Critics say Najib needs to curb the activities of the growing right-wing movement.

"While the government will likely take up positions that support the mainstream Malay-Muslim opinion in the country, having vocal groups like Perkasa and ISMA backing up the government will further alienate some segments, therefore denting Najib's popularity," said Afif Pasuni, an associate research fellow in the Malaysia Programme at the S. Rajaratnam School.

President of the Malaysian Bar, Christopher Leong, said the recent racial and religious tensions were a reminder that Malaysia is still a fairly young nation where much vigilance is needed.

"If Najib is not seen to be handling the extremist elements firmly and decisively, then much of the shine on his star would wane," said Leong. "A substantial part of urban Malaysia is forward thinking and moderate, whilst a significant number in rural areas will follow the direction and tone of a strong leader. Najib needs to be that leader."