Amazon, the online retailing giant, continues to make inroads into the world of logistics. A few months ago, a Chinese affiliate of Amazon filed to be recognized as an ocean freight forwarder with the United States Federal Maritime Commission. Later, it became apparent that Amazon, less than thrilled with the performance of UPS and Fedex, was chartering a fleet of airplanes to carry some of its international and express packages.

Amazon has also announced plans to build a central air hub in northern Kentucky to serve Amazon Prime members.

Now it’s been reported that Amazon has shipped at least 150 containers of goods on cargo ships over the last four months.

Amazon isn’t actually operating its own ships. But, as a freight forwarder, it has the authority to reserve space on containerships on the behalf of clients. According to a report in the Wall Street Journal, deliveries have been made so far to US warehouses from Chinese merchants selling on the Amazon site.

Amazon’s strategy is apparently to offer its Chinese merchants an integrated offering: both a platform to sell on its sight and transportation and logistics services that get products into the hands of consumers in a timely fashion.

In addition to its ocean freight and air cargo activities, Amazon has also bought semi-trailers and and is testing and advocating for the use of drones for last-mile deliveries of merchandise. Amazon wants to operate as much of the logistics chain as possible in an effort to cut down on costs of third-party providers and improve efficiency and delivery performance.

Amazon’s competitors are making moves in the same direction, although not in as comprehensive and dramatic a way. Amazon’s online competitor Alibaba recently signed a deal with shipping giant Maersk Line to allow the booking of space on vessels on Alibaba’s online platform. The service allows existing Alibaba OneTouch registered users to lock cargo prices by pre-paying a deposit.

As with Amazon’s foray into logistics, offering these online services could pose a threat to freight forwarders, the traditional channel for booking space on vessels. The Maersk/Alibaba service allowing cargo owners to book directly with the carrier by way of a website. According to Maersk, the service was launched as part of its strategy to provide digital services for customers.