Estonia's defense minister says his nation is seeking to protect underwater cables in the Baltic Sea by strengthening patrols with neighboring countries.

Hanno Pevkur gave an exclusive interview to NHK in Tokyo on Thursday.

Pevkur commented on a recent series of incidents in which power and communications cables on the floor of the Baltic Sea were damaged.

The minister said he suspects that ships from Russia's "shadow fleet" are responsible. The fleet allegedly transports Russian crude oil while avoiding Western sanctions.

Pevkur said officials are "very seriously" debating what they can do to prevent such "attacks." He said the ships that caused the damage have to take responsibility and pay compensation.

The minister also remarked on US President Donald Trump's insistence that NATO member countries raise defense spending to 5 percent of GDP. This is above the alliance's target of 2 percent.

Pevkur said Western nations did not boost their defense budgets enough to deter Russia from launching its invasion of Ukraine in 2022.

The minister said Russia is now understood to be a threat that needs to be deterred with a message of "force."

Pevkur called on NATO member countries, including his own, to ramp up their defense expenditures to 5 percent of GDP.