US President Barack Obama says Western sanctions imposed against Russia over the Ukraine crisis will remain in place until Moscow fully implements the Minsk agreements.

Speaking at a trade fair in Hanover, Germany on Monday, Obama said that good relations between the US and Russia will only be possible if Russia abides by the peace accords.

"I want good relations with Russia and have invested a lot in good relations with Russia but we need to keep sanctions on Russia in place until Russia fully implements the Minsk agreements," he said.

Russia has been targeted by a series of sanctions imposed by the United States and European Union for allegations that Moscow is arming and supporting pro-Russian forces fighting in eastern Ukraine.

The Kremlin, however, has strongly rejected the accusations.

The sanctions target the Russian energy, banking and military sectors. Moscow has also imposed tit-for-tat sanctions against the EU.

The conflict in eastern Ukraine erupted between government forces and pro-Russia fighters demanding greater autonomy following the overthrow of the country’s former President Viktor Yanukovych in February 2014.

The Minsk II truce deal, reached at a summit between the warring sides which was also attended by the leaders of Russia, Ukraine, France, and Germany in the Belarusian capital city of Minsk on February 11 and 12 last year, introduced measures such as a ceasefire, the pullout of heavy weapons, and constitutional reforms in Ukraine by the end of the year.

The shaky deal has, however, failed to end the deadly violence in the mainly Russian-speaking regions of eastern Ukraine, with both sides trading accusations of breaching a ceasefire agreement which officially went into effect on February 15.

More than 9,000 people have been killed in the conflict.

More NATO deployment on Russian borders

Also on Monday, Obama called on the North Atlantic Treaty Organization (NATO) to deploy more forces and equipments on its eastern frontier with Russia, arguing that Europe has been “complacent” on its security.

"Europe has sometimes been complacent about its own defense," Obama said.

He also underlined that the US-led military alliance has to "bolster our frontline allies in Poland, in Romania and in Baltic States" while also "meet the threat of its southern flank."

In 2014, NATO ended all practical cooperation with Russia over the ensuing crisis in Ukraine and since then has been expanding its presence in Poland and the Baltic nations in order to deter what it calls Russian threat.