Russian President Vladimir Putin (photo via AFP)

President Vladimir Putin has warned that Russia will act if the US-led NATO military alliance crosses its red lines in Ukraine.

Speaking at an investment forum in Moscow on Tuesday, Putin said the expansion of NATO military infrastructure in Ukraine was a red line he hoped would not be crossed.

The president further said Moscow would view the deployment of certain offensive missile capabilities on Ukrainian soil as a trigger.

If some kind of strike systems appear on the territory of Ukraine, the flight time to Moscow will be 7-10 minutes, and five minutes in the case of a hypersonic weapon being deployed. Just imagine, Putin said. What are we to do in such a scenario? We will have to then create something similar in relation to those who threaten us in that way. And we can do that now.

Elsewhere in the speech on Tuesday, Putin praised Russia�s planned investment in expanded military education, hypersonic weapons, and intercontinental ballistic missiles. He said Russia had just successfully tested a new sea-based hypersonic missile, which would be in service at the start of the new year.

Russian Foreign Minister Sergei Lavrov on Tuesday accused NATO of deploying a significant amount of military hardware near Russia�s borders. The top Russian diplomat said Moscow would respond to security threats from Western countries and Ukraine if necessary.

The developments came against the backdrop of Russia�s deteriorating relations with the United States and the European Union (EU). Earlier, the United States and Britain warned Russia over massing troops on the border with the former Soviet republic.

NATO Secretary General Jens Stoltenberg said on Tuesday Russia will pay a high price if it uses force against Ukraine.

We have different options and we have demonstrated over the years, in reactions to Russia�s previous use of military force against Ukraine, that we can sustain heavy economic and financial sanctions, political sanctions, Stoltenberg said as he arrived for a meeting of NATO foreign ministers in Latvia.

Washington and its allies have already imposed sanctions on Russia over alleged cyberattacks, human rights violations, and activity near Ukraine.

And also the fact that we have increased our presence here in the region, both in the Black Sea region but also in the Baltic region, in the air or land and at sea, is a direct reaction to the Russian military incursion into Ukraine, the illegal annexation of Crimea, the NATO chief said.

In his annual state-of-the-nation speech back in April, Putin had warned Russia�s rival powers against threatening his country, vowing a tough response to anyone who crossed Moscow�s red lines.

The Kremlin has warned that the US and NATO are turning Ukraine into a powder keg by increasing arms supplies to Kiev and inflaming tensions in the country�s volatile east, where government forces are fighting ethnic Russians.