Britain and Austria on Tuesday summoned Russia's ambassador for talks, after the Kremlin ordered troops into two Moscow-backed rebel regions of Ukraine.

"This morning the foreign office has summoned the Russian ambassador," British Prime Minister Boris Johnson's official spokesperson told reporters, after the prime minister said London would "hit Russia very hard" with targeted sanctions.

Austrian Chancellor Karl Nehammer said his country has summoned the Russian ambassador to protest Moscow’s breach of Ukraine’s sovereignty.

Nehammer said Austria supports the European Union’s approach of imposing sanctions against Russia step by step, starting with a formal decision Tuesday afternoon by the bloc’s foreign ministers.

"There is a variety of sanctions options that now need to be used in a targeted way because we have to assume that we haven’t yet reached the peak of the escalation," he told reporters in Vienna.

Nehammer also assured Austrians that even if Russia were to stop delivering natural gas immediately, "the energy supply is secure."

Authorities in Vienna are also stepping up surveillance of potential cyberthreats to Austrian government institutions. The country’s Foreign Ministry was targeted in a cyberattack two years ago that was traced to Russia.

Russia said its recognition of independence for areas in eastern Ukraine extends to territory currently held by Ukrainian forces. The statement Tuesday further raises the stakes amid Western fears that Moscow could follow up on Monday’s recognition of rebel regions with a full-fledged invasion of Ukraine.

Kremlin spokesperson Dmitry Peskov said that Russia has recognized the rebel regions’ independence "in borders that existed when they proclaimed" their independence in 2014.

Ukrainian forces later reclaimed control of a large part of both regions during a nearly eight-year conflict that has killed over 14,000 people.