NATO members will hold a meeting in Brussels to discuss the situation in Ukraine amid simmering tensions between Russia and the West.

NATO members will hold a meeting in Brussels to discuss the situation in Ukraine amid simmering tensions between Russia and the West.

NATO Secretary General Anders Fogh Rasmussen said in a message posted on Twitter that the meeting will be held in Brussels, Belgium, on Sunday to discuss the Ukraine crisis.

“North Atlantic Council (NAC) will meet tomorrow followed by NATO-Ukraine Commission,” Rasmussen tweeted.

The NAC meeting, consisting of the permanent representatives of NATO member states, will take place at 1:00 p.m. local time (1200 GMT). The NATO-Ukraine Commission meeting will be held three hours later.

The meeting comes after Ukraine’s interim government called for NATO support against Russia, whose upper house of parliament approved on Saturday a presidential request to deploy troops to the Crimea region in southern Ukraine.

Meanwhile, US officials told CNN that Washington is stepping up its intelligence and surveillance operations against Russia in order to get “inside the Russian decision-making cycle” regarding the situation in Ukraine.

During a phone conversation with Russian President Vladimir Putin on Saturday, US President Barack Obama expressed “his deep concern over Russia’s clear violation of Ukrainian sovereignty and territorial integrity.”

Obama called on Putin to order withdrawal of Russian forces from Crimea back to their bases, warning that Moscow’s refusal would “impact Russia’s standing in the international community.”

Putin has said that the parliament’s decision is justified, adding that “Russia retains the right to protect its interests and the Russian-speaking population” in Ukraine’s southern areas.