## 1 Introduction  
Container liner shipping is a cornerstone of global trade, enabling the efficient transport of goods across continents and supporting much of the world's economic activity [1]. In 2025, however, the transpactile shipping market and the broader containerized ocean transport system are experiencing significant disruptions due to new U.S. Section 301 actions targeting ships built in China or operated by Chinese companies [2, 3, 4]. These measures impose phased port surcharges, effective after a 180-day grace period starting 17 April 2025, with fees for Chinese ship owners/operators beginning at $50 per net ton per U.S. voyage and escalating to $140 per net ton by 17 April 2028 [5]. For China-built ships operated by non-China entities, fees start at $18 per net ton (or $120 per container unloaded) and rise to $33 per net ton (or $250 per container) by the same date, applied up to five times annually per ship [5]. Additionally, the policy mandates that a growing share of U.S. exports, such as liquefied natural gas (LNG), be carried on U.S.-operated ships, starting at 1% in 2028 and increasing to 15% by 2047 [2]. These measures have already caused significant disruptions across key sectors. In the coal sector, ship owners are refusing U.S. coal shipment contracts due to the cost increases, halting $130 billion in exports within 60 days, as the fees have raised delivered coal costs by up to 35% [6]. Agricultural exporters of corn, soybeans, and wheat are struggling to secure ocean freight since May 2025, incurring additional transportation costs of $372 million to $930 million annually [6]. Energy exports, including LNG and oil, are being curtailed due to the absence of non-China-built ships, significantly impacting shipments [6]. Operationally, carriers are suspending routes to smaller ports like Oakland in favor of larger hubs like Los Angeles, causing congestion and equipment misallocation [7]. Industry estimates indicate the fees are adding $600-$800 per container, costing the shipping sector $20 billion annually and increasing consumer prices [7]. These disruptions highlight the urgency and scale of the policy shock, underscoring the need for stakeholders to adapt swiftly to mitigate economic fallout. Liner operators, already navigating a highly competitive and volatile market [8], must now grapple with these profound regulatory changes in addition to existing challenges such as fluctuating demand, rising operating costs, and increasing ship heterogeneity stemming from fleet expansion and alliance strategies [8; 9]. This significantly complicates key decisions in operational management [9], including ship routing, fleet deployment, and transport demand acceptance, which must be carefully balanced to maintain competitiveness [10]. The introduction of such significant port surcharges based on ship origin and ownership fundamentally alters ship routing and deployment decisions. Prior studies on ship routing and scheduling emphasize that changes in cost structures, such as the imposition of new regional fees, directly affect optimal fleet routing, port call patterns, and service frequency [4; 11; 12]. When operational costs increase on specific routes or port calls, liner operators have strong incentives to adjust their deployment, potentially discontinuing routes that include high-fee ports to minimize surcharge exposure [4]. Empirical research and optimization models show that fleet deployment decisions are highly sensitive to regulatory and cost-driven shocks [13], with dynamic re-routing occurring not only in response to fuel price shifts and emission control area (ECA) regulations, but also as shippers and carriers seek least-cost pathways under new port or trade restrictions [14]. Consequently, shipping lines have begun reviewing fleet composition, revisiting newbuilding strategies, and considering detaching beneficial ownership links to avoid U.S. surcharges, potentially transferring China-built ships to non-U.S. trades or substituting other nations' builds into U.S. lanes [2; 4].